The Exposure Family: Aperture, Shutter Speed and Metering

Knowing how to affect the exposure on your photographs can
make the difference between a great shot and a shot of some unrecognizable
white blob with no borders or color.And
just like any other aspect of photography, there are many elements coming into
play when dealing with exposure.Aperture, shutter speeds, metering and light sources all have to be
considered when adjusting exposure.Once
you figure out which combinations work best for different situations, you will
be able to reference those combinations you have mentally preset instead of
fiddling with your camera wasting precious time.

Exposure refers to the amount of light exposed onto the film
or image sensor during a shutter cycle.A shutter cycle is the amount of time the shutter is open for a single
picture; more commonly known as shutter speed.A light source is anything and (unfortunately sometimes) everything that
emits light.Metering is measured three
different ways.Each method analyzes
what is in the frame and determines how much light is needed in order to
properly expose the image.

·Center-Weighted Metering: The image is divided into
segments predetermined by the camera.All of the segments are analyzed but the camera exposes what is in the
frame to better suit the center section.

·Multi-segment or Matrix Metering: It places
reference points across the entire frame and exposes the shot for the average
of those reference points.On most
cameras, this is the exposure default.It works great in a well balanced image but when there are great
variations in light across the frame, it will expose the shot
inconsistently.

·Spot Metering:Spot metering gives the user the most control.One spot in the frame is evaluated and
exposed to that individual reference point.The photographer can normally adjust and move that spot according to
their needs.

With these powers combined, you can be Captain
Exposure.Just kidding, you'll still be
you but you will have a great picture.

In order to work on your mental presets for exposure, take a
look at the pictures below.The first
group of shots has the same aperture setting with increasingly short shutter
speeds.You can see how they work
together or against each other.The ISO
for all the pictures is set to 100.They
were all taken within 5 minutes of each other so the light is the same as well.
This little exposure experiment was conducted so you wouldn't have to (but I
completely suggest doing it anyway so you can see for yourself how your camera
is going to react to different settings).

Aperture: 4.5 Shutter
Speed: ¼

I had to put a border around the image so you knew it was
even there.Obviously, this combination
can be scrapped for this particular light source.

Aperture: 4.5 Shutter
Speed: 1/100

Now that you can see color, you can also see that this image
is overexposed.Overexposure happens
when too much light hits the sensor due to the shutter being open for too
long.The colors appear washed out and
the brighter parts of the picture are highlighted too bright.

Aperture: 4.5 Shutter
Speed: 1/200

This is getting closer to being balanced on all fronts.The highlights are less...highlighted; you can
start to see a door on the shed behind the tree which wasn't apparent in the
last version.Still, there is more
potential for the color to be richer, deeper and less...bright.

Aperture: 4.5 Shutter
Speed: 1/400

You can see a major difference in the color of the sky and
the grass with this shutter speed.But
it still isn't quite there.Using the
real natural elements as a reference point, there is more to see than this shot
allows.

Aperture: 4.5 Shutter
Speed: 1/1250

Look at that: a blue sky, green grass, pink flowers, a blue
door frame, a nice shadow underneath the tree and even some clouds with good
texture and depth.If you look hard
enough, you can even see the lovely telephone lines strung over the
houses.Shadows are just as important in
a correctly exposed image as the highlighted parts are.The contrast is what gives your picture depth
and interest.Getting the exposure right
is like putting a magnifying glass to all the details in the shot, showing off
every part of the picture.

Aperture: 4.5 Shutter
Speed: 1/4000

Clearly, underexposure can also ruin a shot.Suddenly, eleven in the morning turns into six
in the evening.This is handy knowledge
if you are in fact trying to get a night shot and only have time to take
pictures in the middle of the day, but that technique is not all that
practical.Everything is cast in shadow
taking away all the gorgeous color.

Another way to alter exposure is to leave the shutter at a
particular speed and alter the aperture setting.Aperture, also referred to as an "f/stop", is
basically the size of the hole in the lens when the picture is taken.Technically, it's the fraction of the focal
length of the lens at its biggest.Explaining what that means in length involves math and I stopped doing
math a long time ago.The important
thing to remember about aperture is that the smaller the number you see on the
screen, the larger the aperture really is.For example: f/2 is the smallest f/stop most cameras will go, but that
allows in the most light possible.Conversely,
f/22 is the biggest number but allows in the least amount of light.Got it?Good.

In this second set of pictures, you'll see that the shutter
speed stays the same at 1250, but the aperture changes.

Aperture: 3.5 Shutter
Speed: 1250

Aperture: 5.6 Shutter
Speed: 1250

Aperture: 7.1 Shutter
Speed: 1250

Aperture: 9.0 Shutter
Speed: 1250

Aperture changes more than just how much light comes
in.It also dictates how much of the
picture will be in focus.An aperture
with a large number will mean that most of the picture will be in focus.Vice versa, a small aperture will have a more
focused focus.The pictures above are not
a very good example of that.Because
there isn't too terribly much to look at past the tree, there is no variation
of what is in focus.You can see how
aperture and shutter speed play off each other.And if you really pay attention, you can see how two different
combinations will produce the same effect on the final picture.

Larger aperture settings (smaller number, remember?) work
best when you need those nitty gritty details, as in portrait and wildlife
photography.That is also a good time to
use spot metering; find that spot that has the best light that you want for the
whole image and use that.Smaller
apertures work best for landscape photography or when you need the whole grand
picture to be in focus.Multi-segment or
matrix metering is your best bet for that type of photography as well.

Now after all that has been said and done, technology
masters out there have successfully made this entire article unnecessary by
manufacturing light meters.They tell
you everything you need to know about correctly exposing your image; it gives
you a read out that you then program into your camera.There are different kinds of meters for
different kinds of jobs done by different kinds of photographers, and this
article is a great explanation for all of that.So now that you have wasted your time reading
this article, go read the explanation of the different kinds of meters and buy
one.It will save you time and make you
look like an awesome professional who knows how to get the job done.

Maggie O'Briant recently graduated from Florida State University with an English Literature degree. She is currently a freelance writer and photographer. She currently lives in Hawaii with her husband and giant baby.